As it's unlikely Gatiss will be appearing as 'normal', Blogtor wonders if the pictures included here, from both trailers from Series 6, Part 2 are of the Sherlockwriter in action. Judge for yourself. Click on the pics for bigger versions. Mark Gatiss has also written a story for the series, Night Terrors

ETA: The Radio Times has confirmed that Mark Gatiss will star in in the episode now titled, The Wedding of River Song.

ETA (Sep 21): Blogtor can confirm that is IS Gatiss. His character name is Gantok.